in diameter; the back wheel was smaller, only 1.5 metres (5 feet) high. 1916 Trans-Siberian Railway The longest railway in the world. 1916 Optophonic piano Soviet Russia and Soviet Union Late 1910s 1917 Socialist realism A style of realistic art which was developed in the Soviet Union and became a dominant style in other socialist countries. 1918 Air ioniser By Alexander Chizhevsky 1918 Budenovka By Viktor Vasnetsov 1918 Ushanka 1918 Jet pack (not built) 1919 Film school The Moscow Film School 1919 Theremin By Léon Theremin 1919 Constructivism (art) An artistic and architectural philosophy which was a rejection of the idea of autonomous art. The movement was in favour of art as a practice for social purposes. 1920s 1920s Constructivist architecture A form of modern architecture that flourished in the Soviet Union in the 1920s and early 1930s. It combined advanced technology and engineering with an avowedly Communist social purpose. 1921 Aerial refueling By Russian-American aviation pioneer, inventor, and influential advocate of strategic air power, Alexander P. de Seversky 1923 Iconoscope By Vladimir Zworykin 1923 Palekh miniature Also Russian lacquer art, Kholuy miniature, Mstyora miniature 1924 Flying wing By Boris Cheranovsky 1924 Optophonic Piano By Ukrainian painter and sculptor, Vladimir Baranov-Rossine 1924 Stem cells By Russian-American scientist, Alexander Maximow 1924 Primordial soup hypothesis (Abiogensis) By Aleksandr Oparin 1924 Diesel electric locomotive Russian locomotive class E el-2 1925 Interlaced video Interlaced video is a technique of doubling the perceived frame rate introduced with the composite video signal used with analog television without consuming extra bandwidth. It was first demonstrated by Léon Theremin in 1925. 1926 Graphical sound By Pavel Tager and Aleksandr Shorin 1927 Light-emitting diode by Oleg Losev 1927 Polikarpov Po-2 biplane The most produced biplane in the world. 1928 Gene pool by Alexander Serebrovsky 1928 Rabbage Rabbage or Raphanobrassica, was the first ever non-sterile hybrid obtained through crossbreeding, which was an important step in biotechnology. It was produced by Georgii Karpechenko in 1928. 1929 Cadaveric blood transfusion by Sergei Yudin 1929 Kinescope By Vladimir Zworykin 1929 Pobedit Pobedit is a specialized alloy that is close in hardness to diamond (85-90 on the Rockwell scale). It was created in the USSR in 1929 and was used in mining, metal-cutting and as a material for special mechanical parts. Later a number of similar alloys have been developed. 1929 Teletank / Military robot 1930s Spring-loaded camming device by Vitaly Abalakov Abalakov thread